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Xinjiang University (2018)

The Study on the Coexistence Mechanism of Plant Species in Desert Ecosystem

蒋腊梅;

Titre : The Study on the Coexistence Mechanism of Plant Species in Desert Ecosystem

Auteur : 蒋腊梅;

Grade : Master’s Theses 2018

Université : Xinjiang University

Résumé
he mechanism of species coexistence is a theory that studies the function of each species and produces the existing state.In recent years,this mechanism has become a major focus of ecologists.The research areas mainly focus on tropical forests,tropical prairies,temperate broad-leaved forests and other areas,which lack in-depth study on the coexistence mechanism of plant species in temperate arid areas.Therefore,this paper takes the community of wetland desert vegetation in Ebinur as the research object,combining the related theory of species coexistence mechanism,using the method of zero model simulation,species diversity distribution curve,correlation analysis and redundancy analysis and competition model,to discuss the distribution change,the change of plant function characters and the competition of species.The effects of ability on niche processes and neutral processes are discussed,and their respective roles in species coexistence are elaborated.The results show that :(1)120 trees and shrubs and 90 herbaceous samples can be divided into two types of high water,high salt and low water and low salt,according to the K mean clustering method.(2)The difference of organic carbon SDNN from the leaves of woody plants was very significant(P<0.01),and the variation coefficient of total phosphorus in leaves was significantly higher than that of random zero model(P<0.01).The variation coefficient of organic carbon and SDNN of woody plants under low water salt gradient were less than the zero model predicted values,and the difference was very significant(P<0.01).The mean value was significantly greater than the zero model prediction value of the members of the woody plant community.The difference between SDNN and model was very significant(P<0.01) ;the measured mean,coefficient of variation and SDNN of leaf weight of leaves The value is significantly less than zero model predictive value(P<0.01),and the measured SDNN value of dry wood density is significantly less than zero model predictive value(P<0.05).The SNDD value of total nitrogen,total phosphorus and specific leaf weight of herbaceous plants under high water salinity gradient was significantly less than zero model predictive value(P<0.05).The variation coefficient of total nitrogen,total phosphorus and specific leaf weight of herbaceous plants under low water salt gradient was significantly less than that of model values(P<0.05).(3)The analysis of species diversity pattern found that the optimal model of the degree distribution curve of herbaceous plants under the gradient of high water and low water salt was the compound community zero sum polynomial model.The optimal model of woody plants is Volkov model under high water salt gradient,the best model of low salt water woody plants is lognormal model.(4)Under the gradient of high water salt,the distribution of woody plants was more scattered,and under the low water salt gradient,the canopy area,plant height and number of plants were obvious niche differentiation with the change of water and salt gradient,and the correlation between the building groups and the environmental factors under the high water salt gradient was lower,and the limit phase was lower.Similarity is the main role that causes the relationship between the species and the environment,while the low water salinity gradient is very high.The environmental screening effect is more prominent on the coexistence of specie s.(5)The species competition in the woody plant community in this study area,and the intraspecific competition is more obvious ;the average interspecific competition of Populus euphratica is greater than the average intraspecific competition regardless of the high water salt gradient or the low water salt gradient.Nitraria schoberi also have the same rules Halimodendron halodendron prickly has the opposite rule.The competition law of Reaumuria soongorica is more special,and the average intraspecific competition is greater than the average interspecific competition under the high water salt gradient,and the average interspecific competition is larger than the average intraspecific competition under the low water salt gradient.

Mots clés : desert ecosystem; zero model; species coexistence; niche theory; neutral theory;

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Page publiée le 24 avril 2019